"For What It's Worth (Stop, Hey What's That Sound)" (often referred to as simply "For What It's Worth" ) is a song written by Stephen Stills. Performed by Buffalo Springfield, it was recorded on December 5, 1966, released as a single on Atco Records on December 23, 1966.

Although "For What It's Worth" is often considered an anti-war song, Stephen Stills was inspired to write the song because of the Sunset Strip curfew riots in November 1966—a series of early counterculture-era clashes that took place between police and young people on the Sunset Strip in Hollywood, California, beginning in mid-1966, the same year Buffalo Springfield had become the house band at the Whisky a Go Go on the Sunset Strip. Local residents and businesses had become annoyed by how crowds of young people going to clubs and music venues along the Strip had caused late-night traffic congestion. In response, they lobbied the city to pass local ordinances stopping loitering, and enforced a strict curfew on the Strip after 10 p.m. The young music fans, however, felt the new laws infringed upon their civil rights.